Acoustic Emission-Based Identification of Discontinuous Plastic Flow in Austenitic Stainless Steels

Discontinuous plastic flow (DPF) in austenitic stainless steels at cryogenic temperatures is typically identified by serrated stress–strain responses. Here, acoustic emission (AE) is used to probe deformation during uniaxial tensile tests of 304, 316L, and N50 steels at 4 K. Pronounced AE activity is detected well before stress drops, revealing discrete precursor events. The results show that DPF is preceded by progressive microstructural reorganization and establish AE as a sensitive tool for identifying plastic instability.